I believe Derek Acorah does fake it sometimes, but i dont believe he is a total fake. Some places may just be cold at the point of time the team arrive (you cant always have a full net of fish) i think a majority of people would be pushed into making a few odd noises, and come up with pre-knowledge , for the worry of the show going off air. He was quite accurate on the three mediums with Colin Fry and Tony Stockwell. The trouble with derek is that he is very theatrical and a little ridiculed because of his OVER-ACTING

MEDIUM RATING:

Colin Fry 9-10
Tony Stockwell 8-10
Derek acorah 6-10
John Edward 9-10 (goes on a bit )
James Von Prague 4-10 (if anyone is a fake it's this guy)